Jarring tool



Nov. 27, 1945. A. l.. ARMEN'rRouT JARRING TOOL Filed Aug. 12, 1941 2 sheets-Sheet. .1

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Nov. 27, 1945. l A. 1 A-RMENTROUT 2,389,710

JARRING Tool.

. Filed Aug. l2. 1941 2 Sheets-Sheet 2 67 iK 3g Patented Nov. 27, 1945 UNITED STATES OFFICE JARRING TooL Arthnr L. Armentrout, Long Beach, Calif. Application August 12, 1941, Serial No. 4506,465

(C1. 255g- 27) j 7 Claimsihie invention relates te well towels and relates more yparticularly to jarring tools useful in removing ebieets that have beeeme geliebt iii. Welle A general object of this invention is to provide practical and very eirective jarring tools.

Many types of rotary jars have been developed to free or jar loose objects caught in wells but the majority of the jars in use have rnarlged limitations and disadvantages. One general type of ier new irl. use embodies e hammer eeilieied. by a spring which is either compressed by a pull on the' shiiis String 01" er e rotary @am meehanism. This spring actuated type of jar is ineiective for most jarring operations because the space limitation of a well tool prohibits the employment of a Suiiieieiiiiy Sirene Spring Another general type of jar now in use utilizes the stretch in the fishing Sirius te eleiein the J'eiiiiie bleW- This ef iieeee.- sity, subjects the string tov dangerous heavy tensile strains and subjects the lljroisting cable to severe wear. Further, the ,sudden` release of the last named type of jar momentarily interrupts or relieves the tension on the fish and it is impossible to obtain a jarring action while maintaining an uninterrupted or unrelieved pull on the sh. A third general type of jar has been proposed in which the hydraulic pressure or hydrostatic pressure of the well fluid is employed to actuate the jarring hammer. The hydraulic pressure is slow in its action and is unable to develop sufficient dynamic inertia to produce an efficient jarring blow.

An object of the present invention is tov provide a jarring tool operable to produce a very heavy and effective jarring blow. AThe jar of the present invention is operable to produce a jarring blow of great magnitude, being operable to deliver a jarring action stronger than the action of the tools now known and used.

Another object of this invention is to provide a Well jar operable to produce one or successive jarring blows of the required or desired magnitude without straining or endangering the operating string and without subjecting the' cables or other equipment to excessive wear or strains.

Another object of this invention is to provide a jarring tool in which the hammer element is moved at a tremendous lspeed and with great force to develop dynamic inertia of the greatest magnitude and thus produce a mosteiective jarring blow. The hammer element of the present tool may be operated at a velocity and under a force far beyond the capabilities of previously introduced tools.

Another object of this invention is to provide a jarring tool of the character referred to operable to impart or produce" jarring blows of great intensity"while maintaining any selected pull or tension on 'the operating string. The magnitude of lthe blows struck 'by the hammer is not dependentA upon the tension applied to the stringand the operation of Vthe jar' does not necessitate releasingvor relieving the tension maintained on the'st'ring so that `thejarring action may be produced with any selected tension or pull'r'n'a'intained on the shror object'being'jarred.

Another object ofthis'invention is to provide a jarring tool that may be readily conditioned to provide jarring-'blows of any selected or required rnagnitude"`and,` if desired, may be'conditioned to utilize the Ahigh` hydrostatic pressures in tlievrell to increase the'magnitude of the blows without a lssin the velocity of movement of ihe hemmer'eleiiieiii- Another object of this invention is to provide a jarring tool that/may be'operated repeatedly and continuously for along period without a reduction in the lmagnitudeof the jarring blows.

A further 'object of this" invention is to provide aneffective 'jarring tool of the character above referred to'that is easy to cliperateand thaty permits the ready control and operation of the shing tools and other equipment connected in or attached to the operating string.`

The various objects and features of my invention will be fully understood from the following detailed description oi typical preferred lforr'ns and applications of my invention, throughout which description reierenc is made to th'ac`v eempeei'iiie drawings iii Wiiieii Fig.v l is a side elevation of one form of tool of the invention connected in a well string above the object to be jarred. Fig. 2 is an enlarged fragmentary vertical detailed sectional view taken substantially as indicated by line 2*-2 on Fig. 1 showing certain parts in elevation.r Fig. 3 is a transverse detailed sectional view taken'as indicated by line 3 -3 on Fig. 2. Fig. 4 is an'enlarged central'longitudinal detailed sectional vView of the principal parts of the jarring tool showing the hammerv element in its jarring position. Fig. 5 is an enlarged transverse detailed sectional View taken as indicated by line 5-5 on Fig. 4. Fig. 6 is an enlarged fragmentary transverse detailed sectional View taken as indicated by line 6*-6 on Fig. i. Fig. l is a fragmentary longitudinal detailed sectional view of a tooi of the type illustrated in Figs'. 1 to 6, inclusive, with a slight modiiication. Fig. 8 is a side elevation of the lower portion of a well drilling string carrying an impact bit illustrating the form of tool of Figs. 1 to 6, inclusive, connected in the string to operate the bit, with certain of the parts of the jarring tool appearing in longitudinal cross section.

Figs. 1 to 7, inclusive, of the drawings illustrates a form of tool actuated or operated by rotation and adapted to produce an upward jarring action. The tool of the invention illustrated in Figs. 1 to 7, inclusive, may be said to comprise, generally, a hollow or chambered body which I will term cylinder I0, a mandrel II connected with the cylinder I for relative rotation, a ham-` mer element I2 in the cylinder IIl, means I3, preferably interrupted thread means, operable upon relative rotation between the cylinder I0 and mandrel II for actuating the hammer element I2 in one direction, means I4 providing for the introduction of a gas under pressure into cylinder I0 to act on the element I2 for suddenly and forcibly moving the hammer element I2 in the other direction, and releasable means I5 for connecting the cylinder I0 and mandrel II against relative turning whereby rotation may be transmitted through the tool. When I use the term cylinder in referring to the body-like element I0 I use that term broadly and do not conne myself specifically to a part or element which is strictly a cylinder. The means I3, which is shown and described specifically as an interrupted thread means, is broadly a cam means designed to perform the desired function.

In the particular application of the jar illustrated in Figs. 1 to 6, inclusive, the cylinder I0 is the lower principal element of the tool and is connected with the object to be jarred or with the lower portion S of the operating string, which in turn is connected with the object O to be jarred through the medium of a. fishing tool, or the like, not shown. In this case the mandrel II is connected with the upper portion of the operating string S, that is, the main portion of the string which extends to the top of the well. The cylinder I0 is an elongate hollow body-like structure provided with a central longitudinally extending chamber or cylinder proper I6. A sub I1 has a pin I8 threaded in the lower end of the cylinder I0 and may serve to connect the cylinder I0 with the lower section I5 of the operating string. Sealing gaskets I9 are arranged between opposing surfaces of the cylinder I0 and the sub I1 to assure a fluid tight seal between the cylinder and sub. A head 20 has a pin 2| threaded in the upper end Vof the cylinder I0 and sealing gaskets 22 are arranged between opposing surfaces of the cylinder and head to provide a fluid tight connection. The upper portion of the cylinder I0 below the pin 2l has an nturned part providing a downwardly facing shoulder which I will term the anvil 23. The anvil 23 is annular and of substantial area.

The mandrel II is an elongate member considerably vsmaller in diameter than they cylinder I0 and arranged to extend downwardly through a central vertical opening 24 in the head 20 so that it projects into the cylinder IS. The mandrel I I is freely rotatable relative to the cylinder I0 and is held against longitudinal movement with respect to the cylinder. An annular flange 25 is fixed on the mandrel II and is received in a socket 26- of the head 23 with considerable clearance. A plug 21 is threaded in the upper end of the socket 26 above the flange 25. Suitable anti-friction bearings 28 are engaged between the under side of the flange 25 and the lower end of the socket 26 and between the upper side of the flange 25 and the lower end of the plug 21. The lower bearing 28 may seat on a carrier or ring 29 set in the lower wall of the socket 26. A packing gland 30 is provided in the plug 21 to slidably seal about the mandrel I I above the flange 25 and bearings 28. Packing 3I preferably of the chevron type is arranged in the sub I1 below the lowermost bearing 28 for sealing about the mandrel II. The construction just described holds the cylinder ID and the mandrel II against relative longitudinal movement while allowing free relative rotation.

It may be preferred to construct the tool so that the circulation uid is diverted around or past the cylinder I0 so that the cylinder -proper IB may be of maximum capacity and need not be complicated by wash pipes, or the like. In the construction being described the tool includes a shell 32 for conducting the circulation fluid around the cylinder I0. The lower end of the shell 32 is threaded with the sub I1 and the shell extends upwardly around the lcylinder I0 with clearance, leaving an annular fluid passage 33. T-he fluid handling shell 32 extends upwardly beyond the head 20 and plug 21 and a member 34 is threaded with the upper end of the shell to close the same above the body assembly. The mandrel I I passes downwardly through a central opening 35 in the member 34 and a gland 36 in the member seals about the mandrel. The, longitudinal fluid passage 31 of the mandrel II terminates in one or more lateral ports 38, which communicate with the interior of the shell 32 above the body assembly. One or more ports 39 are formed in the sub I1 and lead downwardly from the lower end of the passage 33 to a vertical opening 40, which in turn communicates with the lower portion of the operating string S'. It will be seen that circulation fluid from the mandrel passage 31 is free to flow down through the passage 33, the ports 39 and the opening 40 to the lower part of the operating string.

The hammer element I2 is shiftable vertically or longitudinally in the cylinder proper I6 and is controlled and actuated by the means I3 and the gas in the cylinder proper I6. The hammer element I2 is a cylindrical block-like member of selected length and weight. The length and weight of the hammer element I2 are factors controlling in part the intensity of the jarring blow obtained by the tool and may be varied as conditions may require. The hammer element I2 operates in the upper portion of the cylinder I6 and is considerably shorter than the cylinder. In the form of the invention being described the hammer element I2 is non-rotatable in the cylinder I6. Splines 4I are formed on the upper portion of the hammer element I2 and slidably operate in keyways or spline grooves 42 in the wall of the cylinder I6 to hold the hammer element against turning. The upper end of thc element I2 is adapted to strike or hammer against the downwardly facing anvil 23 of the cylinder IIJ. The lower portion of the hammer element I2 is reduced in diameter to leave a downwardly facing annular shoulder 43. A chevron packing assembly 44 is arranged on the reduced lower part of the hammer element I2 and bears upwardly against the shoulder 43. A nut 45 is threaded on the lower part of the element I2 to actuate or compress the packing 44. The packing 44 is designed to seal off high pressures in the cylinder below the hammer element l2.

The means ls, which is; broadlra eau-1l` means sind.; iii. tho preferred form of. the inventionis. an. interrupted thread structure, is operable upon relative; rotation line-ween: the; inaildrol. land; the cylinder ID. tomovethe-hammer element-L2. longitudinally a given distance: end uien, release.- the hammer element for for-.cible aetuationbr the body o5 gas in the tool; The meal-:ArsE I3;- in the Particular foi-'mi illustrated includes a, long-itudi-.I nal socket 4e ofk substantialy depth, exte,li-ding-Y downwardlyin the hammer-=, len1entYAY I-2 to ,receivethe lower portion of the mandrel- I I-. The-meansl-3Y further includes cooperating cams orthreadson the wall of the socket 4.6` andY the lower-pore tion of the; mandrel ll for producing; downward movement oi thehammerelement I2.; A heavy.- steeply'pitohed thread. 4l is provided on the wall of the socket 46.. Ih.Y the oase of a righthand jarring; toolv thev thread ill.- is lefthand` and-leads downwardly from the top of the-hammer element; l2.. The thread I1k isinterrupted, being pro.-v vided with a Vertical gap or channel 48 of Sub,- stantial; width.

The lower part of` the mandrel II` has. a-` longie tudinall-y extending row of thread parts 49 which cooperate with the thread 41A. The width or circumferential extent of the thread parts 48 is slightly less than the width of the channel All so-that the thread par-ts. may travel longitudinally through the channel. The thread 41 preferably has a flat normall upper surface engagedy by cora responding surfaces on the parts 4.3 and has a pitchedlower surface cooperating withV similar pitched upper surfaces on the parts 4.9,., Upon turning of the mandrel II to the right the` co-v operation of the thread parts 49 with the thread 4'I- moves or forces the hammer element-L2. downwardly. At the completion of approximately one revolution the thread parts 49 move into. the channel 48 and allow the hammer element |52 to suddenly and forcibly move` upwardly under the action of the means I4. It is preferred. to construct the thread Illv andr the parts 4.a, to move the hammer element l2` downwardly a maxim-um distance at each operation. splines 4I engaged in the grooves 42 hold the hammer element lf2 against tur-ning during the action j-.ust describedand guide the hammer elsa ment for straight longitudinal movenflent.l

Themeans M provided fory establishingy a.Y body or gas in the tool is an important elementl of the invention. The gas is operable to drive thc hammer element I2 upwardly with great speed and great force upon the release of the means I3 as just described. The gas is operable to deE velop greater hammer speed andk to, impart greater force to the hammer element than the hammer actuating means of prior` jarring tools and may be readily conditioned to. produce blows of selected or required force within a wide range of action. The gas is confined in the portion of the cylinder proper l-l below the hammer ele, ment I2. In accordance with the invention the lower portion of the cylinder proper t6, that is, the portion of the cylinder below the hammer element I2 is pre-loaded or charged with air or other gas under superatmospheric pressure beE fore running the tool into the well for use. The initial pressure in the cylinder proper Vi, that is, the pressure in the lower part of the cylinder proper with the hammer element I-Z in its uppermost position, is one of the important factors determining the intensity of the jarring blow obtained and this initial pressure may be varied within wide limitations.. In. practise, the initial air gas; pressure; the orlinder proper Le marraine-from ,e few; pounds per square inch toa thousand, .oui-ids square iuoh or more- -Wh1 ef the n-ventioncontemplates sealing the ovlin prrr-oper is with o, elven. or selected oonoutwardly to the exterior of the sub. A cheek valve il of; the spring los/ded type isarranged thelowerportion of. the pori. 50. and closes-oui w-ardlv to. prevent. the essereA or discharge of the. contained air orgels-pressure. Theouter-part of the; port it. is.; threaded to reoeive u pio-isili@ Supply lattine and a removable plug 52- is ihreadf edil the high external hydrostatic pressures in the dell', and; to prevent mud, vand the like, from clog-A ging the port; A. second passage 5.3 in. the wellof: the sub il .ioiusihepor-t 5,0 and is equipped with a, valve for relieving the pressures in. the cylinder I, The valve 54; may be of the needle type provided with aI threaded-in plug 55 for heidi-nea it closed and for soo-los the Outer; PQI- tion of; the, passage 531. Upon removal ofthe plus 5a the discharge fitting of a suitable sus or; air container orgas: or air pressure develop.- ingf mea-ns may he threaded in the port 5,'0y to deliver the required airor gas pressure to the cylinder proper- I-Sj. The plug- 52 is replaced upon removal of; the, fitting,l The valve 54 maybe easilyv opened to relieve the pressure in the ovlinder proper t6 as required- 'Ijhe means I4; is such that the initial superatmospherio pressure in the cylinder proper I6 may be ampliiied or increased by the hvdrostotio pressure in the Well. When it is desired to einploy the hydrostatic pressure in the Well to boost nie-initial an or gas chamber in the cylinder proper te. the plug- 512 is removed from the port 5.o. prior to running the tool in the Well. The valve` 5lrem-ains closed to preserve the initial gasor air pressure in the cylinder I6. When.v the,

toolA heen lowered. through the Well to e position where the hydrostatic pressures are in excess!v off; the initial pressure in the cylinder proper I@ the valve 5t opens so that the pressure in the cylinder is increased by the external hydraulic pressure. It is tov be understood that this utilizationl of` the hydraulic pressure is not always essential and, in many cases, the plug 52 is lef-t in the. port 51k to keep. the same closed.

means I4 further includes a mechanism for-transferringair or-gas pressure that may have leaked upwardly past the packing 44 back into the cylinder proper- I6 below thepacking. A port 56 extends upwardly through the wall of the cylinder Ill to the anvil 23. The lower` end of the port 55 is in communication with the cylinder proper I6. The upper end of the port communicates with the interior of the cylinder assembly above the hammer element I2 as at 51 iii Fig. 6. A compressor is arranged in the anvil 23 to be operated by rotation of the mandrel II relative to the cylinder In and the compressor takes air or gas from above the hammer I2 and iorces it back into the cylinder proper I6 below the hammer element. The compressor comprises a radial cylinder 5 8/ formed in the cylinderI II) art ofthe port to, seal the pori. against and carrying a spring urged piston v59. One or more cams 60 on the mandrel II cooperate with a stem 6I on the piston 59 to produce reciprocation of the piston, A non-return check valve 62 is interposed between the cylinder 58 and the port 56 and a similar check valve 62a is provided between the inlet port 51 and the cylinder 58. When the tool is in operation the compressor just described is automatically operated to evacuate air or gas from above the hammer element I2 and discharge it into the cylinder proper I6 below the hammer element to compensate for any leakage of gas or air under pressure past the packing 44.

It will be observed that the hammer element I2 slidably seals with the wall of the cylinder proper I6, the packing 44 at all times maintaining a tight, eiective seal, Accordingly, downward movement of the hammer element I2 by the action of the thread 41 and thread parts 49 produces a negative pressure or vacuum above the hammer element. This creation of the negative pressure accompanies the increase in the super-atmospheric pressure in the expansible fluid under thel hammer element. When the means I3 releases to permit upward movement of the hammer element the vacuum action airs or'supplements the action of the compressed gas under the piston in driving the hammer element upwardly with great force and at a high speed.

The means I5 is adapted to clutch or connect the cylinder I0 and the mandrel I I for the transmission of rotation therebetween when it is desired to control the shing tool or other object below the tool of the invention and is releasable or adapted to be conditioned to permit rotation of the mandrel II relative to the cylinder I0 for the actuation of the jarring tool The means I5 includes the member 34 and a tubular inner member 63 fixed to the lower end of the main operating string S by threads, or the like. The outer member 34 receives the member 63 with suitable working clearance and the mandrel II extends upwardly through a central opening 65 in the lower wall of the inner member to project into the interior of the same. A head 66 on the upper end of the mandrel II carries packing 61 for slidably sealing with the interior 0f the member 63 and is provided with downwardly facing clutchparts B8, Upstanding clutch parts 69 are provided on the lower wall of the member 63 and are engageable with the clutch parts 68 when the string S is raised. When the lower portion S of the string is engaged with the fish or object O an up-pull may be placed on the string S to engage the clutch parts 468 and 69.

It is usually preferred to maintain an up-pull on the string and the sh during the jarring operation and this tension or up-pull holds the clutch parts 68 and 69 in engagement so that rotation may be transmitted from the string S to the mandrel I I to operate the jar.

The means I5 further includes a pair of diametrically opposite J grooves 'I0 in the wall of the outer member 34. The long arms of the grooves 1U extend downwardly from the top of the member 34 and the lateral arms of the grooves have upwardly extending pockets 1I. Pins 12 are fixed to the inner member 63 and are adapted to cooperate with the grooves 10. When the pins 12 are engaged in the pockets 1I they are adapted to transmit rotation between the mandrel I I and the body I0 in both directions. By lowering the string S slightly and then turning to the left and then raising the string the pins 12 may be withdrawn from the grooves 10 to above the member 34. Slight continued upward movementfengages the clutch parts 69 with the clutch parts 68. Thus, the string S is disconnected from the cylinder I0 and is clutched with the mandrel II`. To reengage the string S with the cylinder I0 for the transmission of rotation to the cylinder, the string is lowered slightly to bring the pins 12 against the upper end of the member 34. This downward movement of the string S disengages the clutch parts 69 from the clutch parts 68 'and the string S may be turned to bring the pins 12 into registration with the upper ends of the grooves 10. The string S is-then manipulated to reengage the pins 12 in the pockets 1I. The means I5 provides for the free rotation of the string S and mandrel II relative to the cylinder IU and for the transmission of rotation from the string S to the cylinder ID at the will of the operator, and is located above the other parts of the tool where it does not complicate the construction.

In the use or operation of the tool illustrated in Figs. 1 to 6, inclusive, it may be assumed that the tool is to be employed in jarring a sh or object O caught in the well. Prior to lowering the tool into the well air or other expansible and contractible fluid is supplied to the lower portion of the cylinder proper I6 under suitable pressure. The pressure employed may vary greatly and depends upon such factors as the nature of the jarring operation, the capacity ofthe cylinder proper I6, the stroke of the hammer element I2, etc. The valved port 5I) provides for the ready delivery of air or the like, under pressure, to the lower portion of the cylinder proper I6. The plug 52 is usually threaded in the port 50 when the required air pressure has been supplied to the cylinder proper I6. The jarring tool is run into the well on the string S and the string is coupled with the object O by a, fishing tool, or the like, in accordance wtih the usual practice. When the lower portion of the string is being coupled with the object O the pins 'I2 of the means I5 may be engaged in the pockets 1I so that rotation may be transmitted to the fishing tool for its control. With the shing 'tool engaged with the object O the means I5 is released, as described above, so that the string S and the mandrel I I may be freely turned with respect to the cylinder I0. The required or selected up-pull or tension is then put on the string S and the string is rotated to operate the jarring tool.

During each rotation of the string S the thread parts 49 cooperate with the thread 41 t o force the hammer element I2 downwardly and then suddenly disengage from the thread 41 to-allow an upward movement of the hammer element I2. The downward movement of the hammer element I2 produced by the cams or threads of the means I3 compresses the air or gas under the hammer element I2 to greatly increase its pressure and creates a vacuum condition or negative pressure condition above the hammer element. The amount of increase in pressure of the air or gas under the hammer element I2 depends upon the length or volume of the cylinder proper I6 and the stroke of the hammer element. This relationship may, of course, be varied greatly. The downward movement of the hammer element I2 against the already highly compressed air or gas provides a great increase in the pressure so that a very high gas pressure may exist under the hammer element I2, while a substantial negative pressure or vacuum exists above the hammer gasa-7.110

vendofthefshell 32. A packing gland 11,1 in the at .the time the means .|33 releases. When the thread Yparts 49 reachthe channel 48 'the hammer |12 is VYsuddenly thrown up with -a vgreat .force 'resultingfrom lthe instantaneous expansion of the :highly compressed gas .under .the :hammer .aided Abythe negative pressure `a'bove the hammer. 'This forcible movement ofthehammer element .I2 at high speed Ycauses the .hammer .element 'to .strike the anvil 223 'with great "force, The 'impactfgenerated depends upon several vfactors .such ias 4.the weight iof the hammer element I2, :the diameter ofithe hammer element, theimaximum .pressure fcreated under the hammer :.element, :the :length =of therhammer element stroke,fetc. The action justdescribe'd, takes place withfeach rotation .of

thestrin'g 'S .and mandrel .II 'and aiseriescofathe heavy upward `ja'rringblows is usually effective in loosening the sh or .object .O for recovery.

In the event thatJ .it is desired to utilize the 'hydrostatic pressure in the well to augment the vaction of the air or' gasunderlpressure, the `cylinderproper I6 may be charged with .-air or other gas un'der'the selected initial pressure and the tool tis run intothe well-with the plug :52;removed. When the toolY reaches a levelin the well where the external hydrostatic lpressures lare greater thanl the initial gas or air pressureinithe-chamber I6 the valve-5I opens so that thehydraulic pressure is superimposed on thegas pressure. In .this way a very great initial Vgas .pressure may :be maintained in the 4cylinderproper I6 and yet lemploy 'a lcompressible and expansible pressure 'medium for acting on the hannner element I2. `In other words, theair orgas trapped inthecylinder proper I6 under'the'initialpressure applied at'the surface, and with its pressure increased vby the hydraulic pressure applied inthe well,

expands instantaneously -to 'drive the jhammer element I2 upwardly with great speed .fandiorce and is not delayed in its action by the non-expansible well liquid. The jar operates in other respects as described above, the reduced pressure or vacuum above the hammer element I2 assisting in the actuation of the hammer element I2.

Fig. '7 of the drawings illustrates a slight modication of the type of tool illustrated in Figs. 1 to 6, inclusive. In this case a spring I3 is provided in the cylinder proper I6 and is arranged under compression between the lower end of the hammer element I2 and the upper end of the sub pin I8. The parts are proportioned and arranged so that the spring 'I3 is under compression when the hammer element I2 is in its uppermost position against the anvil 23. This compression is, of course, increased when the hammer element I 2 is moved downwardly by the cooperation of the thread 41 and thread parts 49. VThe spring 'I3 assists in driving the hammer element I2 upwardly upon the release of the means I3 and, thus, aids the action of the air or gas under pressure in the lower portion of the cylinder proper I 6 and the reduced pressure or vacuum above the hammer element I2. The various other parts of the tool may be the same, as described.

Fig. 8 of the drawings illustrates a tool of the type illustrated in Figs. 1 to 6, inclusive, employed to operate a percussion bit, or the like. In this case the tool is inverted so that the sub Il is at its upper end and the mandrel I I is connected with the object to be jarred. In the particular application illustrated the protruding lower portion of the mandrel I I is connected with the stem 'I4 of a bit 15. The means I5 is eliminated and a plug member 'I6 closes the lower `member `'1:6 sl-idablysea'ls .about lthe mandrel I I. Theportor portsi `of the .mandrel'I-I communicate `with the interior of :.the'shell v,32 .above vthe member 1.6 so that'the mandrel delivers the circulationfluid to the bit 1.5. The .other ,parts may remain as described above.

In operating the Vequipment illustrated `in Fig. 8 theistringzS is rotated inthe wellwith or without the application of. a ,down pressureon `the jarring ztoolandbit 15. Rotation-of the strings-.results -in-upward `movement of the -hammer element I 2 y:bythe thread .-4.1 .and `thread parts V119 and .the

.sudden `rapid forceful `drivingof the hammer element I2 V:against the .anvil -23., .all .as described above, r'except Athat .fin this case thehammer element t2 is suddenly and'forcibly .driven downwardly against'theupwardly facing anvil. .The .tool .may be invertedvas Vshown .in Fig. 8 .of .the

V:drawings to yoperate as a down jar `.torloosening l:or freeing `objectscaught :in wells and for performing lother operations IWhere .sa downward J'arring actionis required.

Having .described typical lpreferred lforms and applications of my invention, I do notfwish to-,be :limited or4 restricted to the specific `.details :herein yset forth, but wish `.to reserve to.-myself. any variations or` `fmodicaticns l.thatfmay appear to those skilled in 2the .art or falllwithin thescopeof. ,the `following .claims.

. Having described my invention, vI claim:

1. ln a -well tool, two sectionsconnected .for

relative turning andadapted to be interposed ia -well string, one section having fa ,longitudinal cylinder, :a jhammer .shiftable .ein the cylinder,

.means for introducing gas :under ,pressure ,to .the

`cylinder .at zone side .of the hammer, .means roperableby relative turningfof the sections for moving the vhammer longitudinally .against thegas vvunder.lmessureeto.increase said-pressurefand pro- `-duceaflcw ,pressure lcondition at thevother side of the hammer and releasable followingwagiven movement of the hammer to allow the hammer to move in the other direction under the action of the expanding gas and reduced pressure con dition so that it strikes a jarring blow against a section, and means operable by relative rotation of the sections for pumping gas from the cylinder at said other side of the hammer to the cylinder at the rst named side of the cylinder.

2. A well tool for use in a well string including a body having a cylinder, a mandrel entering the cylinder, means connecting the body and mandrel for relative turning, a hammer in the cylinder, the cylinder at one side of` the hammer holding gas under pressure, cam means on the mandrel and hammer operable upon relative rotation between the body and mandrel to force the hammer against the gas pressure to increase the pressure thereof and then suddenly release the hammer to move in the other direction and jar against the body under the action of the expanding gas, and compressor means operable by relative rotation of the body and mandrel for transferring gas from the cylinder at the other side of the hammer to the cylinder at the first named side of the hammer.

3. A well tool for use in a well string including a body having a cylinder, a mandrel entering the cylinder, means connecting the body and mandrel for relative turning and holding them against relative longitudinal movement, a hammer in the cylinder, packing means between the hammer and the cylinder holding gas under pressure at one side of the hammer, and cam means on the mandrel and hammer operable upon rel- `ative rotation between the body and mandrel to force the hammer against the gas pressure to increase the pressure thereof and then suddenly release the hammer to move in the other direction and jar against the body under the action of the expanding gas.

4. A well tool for use in a ell string including a body having a cylinder, a mandrel entering the cylinder, means connecting the body and mandrel for relative turning and holding them against relative longitudinal movement, means for conducting circulation fluid around the cylinder between the mandrel and the end of the body most remote from the mandrel, a hammer in the cylinder, packing means between the hammer and the cylinder holding gas under pressure at one side of the hammer, and cam means on the mandrel and hammer operable upon relative rotation between the body and mandrel to force the hammer against the gas pressure to increase the pressure thereof andthen suddenly release the hammer to move in the other direction and jar against the Ibody under the action of the expanding gas.

5. A well tool for use in a well string including a body having a cylinder, a mandrel entering the cylinder, means connecting the body and mandrel for relative turning and holding them against relative longitudinal movement, releasable means for connecting the body and mandrel against relative turning, a hammer in the cylinder, packing means between the hammer and the cylinder holding gas under pressure at one side of the hammer, and cam means on the mandrel and hammer operable upon relative rotation between the body vand mandrel to force the hammer against the gas pressure to increase the pressure thereof and then suddenly release the hammer to move in the other direction and jar against the body'under the action of the expanding gas.

' 6. In a well tool, 'two sections' connected for relative turning and adapted to be interposed in a well string, means holding the sections against relative rotation, one section having a longitudinal cylinder, a hammer shiftable in the cylinder, packingrmeans between the cylinder and hammer, means for introducing gas under pressure to the cylinder at one side of the hammer, means operable -by relative turning of the sections for moving the hammer longitudinally against the gas under pressure to increase said pressureand produce a low pressure condition at the other side of the hammer and releasable following a given movement of the hammer to allow the hammer to move in the other direction under the action of the expanding gas and reduced pressure condition so that it strikes a jarring blow against a section, said means comprising cooperable interrupted threads on the v hammer and the other section. 1

7. A well tool for use in a well string including a body having a cylinder, a mandrel entering the cylinder, means connecting the body and mandrel for relative turning and holding them against relative longitudinal movement, a hammer in the cylinder, packing means between the hammer and the cylinder holding gas under pressure at one side of the hammer, the portion of the cylinder at the other, side of the hammer being sealed so that movement of the hammer against the gas creates a negative pressure at said other side of the hammer, and cam means on the mandrel and hammer operable upon relative rotation between the body and mandrel to force the hammer against the gas pressure to increase the pressure thereof and then suddenly release the hammerto move in the 4other direction and jar against the body under the action of the expanding gas.

ARTHUR L. ARMENTROUT. 

